Leviticus 16:29-30

29“This is to be a lasting ordinance for you: On the tenth day of the seventh month you must deny yourselves Or must fast; also in verse 31 and not do any work—whether native-born or a foreigner residing among you— 30because on this day atonement will be made for you, to cleanse you. Then, before the LORD, you will be clean from all your sins.